The primary function of Core C is to chart the developmental trajectories through adolescence of language, discourse, attention, spatial cognition, memory and executive function in both normally developing and experimental populations. The Core organization allows us to maximize the efficiency of testing and ensure the smooth flow of information regarding children's testing between the Projects and Cores. It also serves to enhance the consistency, reliability and validity of data collection across Center populations. Core C will have primary responsibility for testing and tracking all normally developing subjects. The experimental populations are those identified with the Population Projects, and include children with early and late brain damage, Language Impairment, Williams Syndrome, and Down Syndrome, and Down Syndrome. These will be tested in close collaboration with Core C on two sub-batteries: A) Longitudinal, off-line: Language, Discourse, Spatial Cognition, Memory, Executive Function; B) Cross-sectional, on-line: Language, Attention and Spatial Cognition. The first sub-battery includes measures to assess later language development, specifically metalinguistic and discourse abilities. By assessing linguistic performance in isolation and in discourse, we address issues of linguistic knowledge versus performance. Using the CHILDES system, Core C will transcribe and code all elicited spoken and written language data. The Attention and Spatial Cognition, Memory and Executive Function Battery includes measures to assess various levels of non-linguistic processing: visual and auditory attention; hemispatial neglect, spatial cognition, verbal and spatial memory, and executive function. These data will permit us to identify association and dissociations within and across the domains of linguistic and non- linguistic cognition. The on-line tasks of Testing Battery B are directly yoked to the neuro-imaging studies (FMRI) and the the ERP studies. The studies outlined in Core C build on our previous research and introduce new lines of inquiry that will inform our understanding of later development in both normal and atypical populations. This new core will centralize our resources and provide a clearly-defined forum for the discussion and investigation of cross-population and investigation of cross-population hypotheses with respect to the development and integration of these basic cognitive systems.